Overweight has doubled in US children in the past two decades with 25% of 6 to 19-year olds estimated to be overweight or "at risk for overweight." Urban minority children are at even higher risk. The results from our comprehensive evaluation of our SEPA funded Phase I &II (1997-2004) project, Linking Food and the environment (LIFE) show that children are very interested in science when it involves an inquiry-based approach and uses content that is personally meaningful, such as food. The specific objectives of this project are to develop, evaluate and disseminate a curriculum, Choice, Control and Change (or C3), that would be an extension into middle school, grade 6 or 7, of LIFE, which is for grades 4-5. More specifically, C3 will (a) provide students clear, conceptual understandings of the complex roles of biology and the 21st century food system in influencing personal behavior, health, and body size;(b) build skills and attitudes that lead to competence or personal control in navigating today's complex food system and sedentary environment;(c) focus on improving healthful eating and physical activity practices as a means to overweight prevention;and (d) increase interest in the health sciences and health science careers. C3 will also provide children the opportunity to meet science and health education standards. After development and formative evaluation in year 1, C3 will summatively evaluated in year 2 in a pretest-posttest intervention, control group design involving 4 New York City middle schools randomly assigned to condition within pairs, with 20 C3 classes and 20 comparison classes (about 1000 students total). The 20 classes in control schools will receive the curriculum in year 3. Evaluation results will be used to revise the program. Dissemination in years 4 and 5 will involve four national sites in addition to New York, with 120 classes (3600 students) being fully funded to receive C3. A leader teacher model will be used to institutionalize C3 to help assure that schools continue to implement C3 after SEPA funding.